For example, in an exhaust gas processing device equipped with a carbon dioxide recovery device that recovers carbon dioxide in a combustion exhaust gas from a boiler or the like by bringing the combustion exhaust gas into contact with amine-containing absorbing liquid and by absorbing the carbon dioxide in the combustion exhaust gas with the absorbing liquid, a micro amount of amines or ammonia is discharged to the outside together with the combustion exhaust gas from which the carbon dioxide is absorbed and removed, and is discharged by the carbon dioxide recovery device. Accordingly, an operator samples the combustion exhaust gas which is discharged in a state where the carbon dioxide in the combustion exhaust gas absorbed and removed in the carbon dioxide recovery device, and measures concentrations of amines and ammonia (hereinafter, referred to as “amines and the like”) which the combustion exhaust gas contains.